The present invention relates to a process to reduce the fouling of equipment for processing petroleum feedstreams. In particular, the fouling is due to the presence of peroxides and hydroperoxides in the petroleum feedstream.
All crude oils contain wppm levels of peroxides and hydroperoxides that were formed by exposure of some crude components, e.g., olefins, conjugated dienes, hydrocarbons containing tertiary hydrogens, pyrroles and indoles, etc. to oxygen in the air. Oxygen, a biradical at room temperature, reacts with these components in minutes (conjugated dienes), to hours (olefins) to weeks (tertiary hydrogens). The presence of even sub-ppm levels of peroxides will lead to fouling of fractionators, heat exchangers, furnaces, etc., and other refinery equipment upon heating. Reaction of peroxides on heating (.about.100-200.degree. C.) initiates molecular weight growth chemical reactions, such as oligomerizations, polymerizations in pure component feeds, inter- and intramolecular alkylation reactions, etc. For example, a peroxide formed from a conjugated diene can react with other conjugated dienes, with pyrroles, indoles, carbazoles, most phenols, naphthols, thiophenols, naphthalene thiols, etc. An indole peroxide can react with another indole, a conjugated diene, etc., along the path to molecular weight growth reactions. When a feed containing a peroxide is mixed with another feed containing, e.g., conjugated dienes, the molecular weight growth reaction can continue. When the level of molecular weight growth exceeds the solubility of the growth products in solution they precipitate out on metal and other surfaces and foul the surfaces forming coke (thermal coking). The oligomerization and polymerization reactions are chain reactions. So, one molecule of a peroxide can react with hundreds of molecules of olefins or conjugated dienes (of same or varying structure). Oligomerization vs alkylation reactions will depend on the relative concentrations of species in a feed (e.g., of conjugated dienes vs. aromatics, especially 2.sup.+ ring aromatics, and phenols, thiophenols, etc.). When there are no peroxides in the feed, no chain reaction initiators, most of these molecular weight growth reactions will be inhibited.